This invention relates to a new tetracycline antibiotic, 7-chloro-4a-hydroxy-8-methoxytetracycline, isolated from an antibiotic complex designated as antibiotic 7273 complex which is produced by fermentation under controlled conditions using a biologically pure culture of the new microorganism Dactylosporangium vescum ATCC 39499.
In a related, commonly-assigned, co-pending application Ser. No. 763,400, filed on even date herewith, another new tetracycline, 7-chloro-8-methoxytetracycline, produced by fermentation of mutants of A. brunnea, A. brunnea var. antibiotica var. nov., ATCC 53108 and ATCC 53180 is disclosed.
In another related, commonly-assigned, copending application Ser. No. 763,742, filed on even date herewith, another new tetracycline, 7-chloro-8-methoxy 2'-N-methyltetracycline, produced by fermentation of Actinomadura brunnea ATCC 39216 is disclosed.